Sound localization

What are the three cues for localizing sound?

interaural level difference, interaural level difference, and interaural spectral difference

Which cue for localizing sound is related to interaural phase difference?

interaural time difference

Which cue is connected to binaural spectral differences like HRTFs?

interaural spectrum difference

What are the cues for localizing sound in the horizontal plane??

ILD, ITD, and IPD

Define qualities of duplex theory

explains left-right and front back dimensions

incorporates intensity and phase/time cues in a frequency dependent manner

ILD was predominately used in high frequencies

ITD and phase were prominently used in low frequencies

Name the qualities of interaural level difference

for high frequency sound, 1500 Hz and above

smaller wavelength than the diameter of the head

sound reflects off the head which causes a head shadow

higher frequencies are smaller than the diameter of the head

True or false: ILD varies as a function of frequency and location of the sound source

true

Fill in the blank: when sound are directly in front or back, the ILD is ____ dB

0

Fill in the blank: when sounds are at 90 degrees azimuth, the largest ILD is ____ dB

20

Describe the relationship between ILD and frequency

when one goes up so does the other

Name the qualities of ITD

for low frequency sounds 1500 Hz and below

longer wavelengths than the diameter of the head

sound diffracts around the head

delay in time between the ears

True or false: ITD does not vary on the position of the sound source

false

Fill in the blank: when the sound is directly in front or back, the ITD is _____

0 ms

Fill in the blank: at 90 degrees azimuth the largest ITD is about ____ ms

0.7

Fill in the blank: the location you will find the smallest ITD is ___ degrees

5

Define functional head size

the time it takes for sound to travel around the head from one ear to the other

True or false: the smaller the animal’s head size, the smaller the ITDs

true!

What are the qualities associated with interaural phase differences in low frequencies?

good separation in phase between near and far ears

Fill in the blank: in interaural phase difference, high frequencies cannot be used for _______ ___________.

sound localization

Fill in the blank: in interaural phase difference in high frequencies, the phase of sound arriving at both ears are __________

identical

Define the cone of confusion

regions of space that have the same ILDs and ITDs

Name some qualities of the cone of confusion

listeners cannot tell if the sounds are in the front or the back or if they are above or below

other cues are needed to leave the cone of confusion

Name the cues for localizing sound in the median plane

monoaural cues, head-related transfer function, and high frequency hearing and sound localization

Name some types of monaural cues help someone escape the cone of confusion

using head movement

pinna picks up the elevation of sound

sound energy absorption by head and pinna as well as sound reflections from the pinna, head, and shoulders via monaural spectral cues

Define interaural spectral cues

helps with elevation and front or back sound localization

help resolve ambiguous sounds from ITD and ILD

What can affect pinna cues and ILDs?

hair/hairstyle

Define transfer function

a graph that shows how a filter will affect sound

Fill in the blank: typical human HRTFs use __________ cues to filter sound

spectral

How can HRTFs in humans demonstrate spectral cues to filter sound?

gives the impression sounds are coming from different locations

can create a virtual audio experience while wearing headphones

depending on the richness of the audio experiences, sound systems that could be used are: stereo, surround, and Dolby Atmos

Fill in the blank: your head will _____ frequencies starting from the wavelength associated with your head

block

What is the average human skull thickness?

~17 cm

What frequencies does the head more effectively block to create a spectral difference?

high frequencies

Fill in the blank: the _____ the head, the higher the frequencies and the more frequencies being blocked

smaller

True or false: having good low frequency hearing is necessary to take advantage of the spectral cues

false; high frequencies

What is the range of human hearing according to the chart on the slides with the other animals?

31 Hz-19kHz

What is the actual hearing range for humans?

20-20,000 Hz

True or false: the smaller the head, the higher the ITDs

false!

What type of sound will provide the listener with the best 3D audio experience?

Dolby Atmos

Species with smaller heads need good _________ hearing to be able to use interaural spectral cues

high-frequency

What significantly improves speech recognition when interfering talkers were facing away from each other?

extend high frequencies

When are extended high frequencies used in audiometric testing?

when patients have a history of chemo, tinnitus, and NIHL

Low frequency information is processed by what?

ITD and IPD

High frequency information is processed by what?

ILD and interaural spectral differences